Liquid fuel injection pump for internal-combustion engines



May 1953 w. E. w. NICOLLS 2,638,053

LIQUID FUEL INJECTION PUMP FOR INTERNAL-CQMBUSTION ENGINES Filed Jan. 9, 1950 Patented May 12, 1953 UNITED STATES PATENT OFFICE LTQUID FUEL INJECTION PUMP FOR INTERNAL- COMBUSTION ENGINE S Application January 9, 1950, Serial No. 137,593 In Great Britain January 13, 1949 2 Claims.

This invention relates to a liquid fuel injection pump having one or more reciprocatory plungers for injecting liquid fuel into the cylinder or cylinders of an internal combustion engine, the pump being of the kind in which the fuel inlet port or each such port is controlled by the as: sociated plunger.

For some purposes, it is desired to be able to advance the instant at which the fuel is injected into the engine with increasing engine speed, and the object of the present invention is to enable this requirement to be met in a simpler manner than heretofore.

In the accompanying drawings:

Figure 1 is a sectional elevation illustrating a pump embodying the invention, and

Figure 2 is a cross section of the pump barrel on the line 2-2, Figure 1.

Referring to the drawings, the greater part of the pump there shown is of known construction. It comprises a pump barrel a (or a plurality of such barrels arranged parallel with each other), the barrel or barrels being secured within a hollow body part b. The reciprocatory plunger is actuated in one direction through a slipper d by a rotary cam c and in the opposite direction by a spring For regulating the output of the pump, the plunger 0 has formed on it in known manner a spill groove g, the position of which in relation to the inlet port or ports 11. in the bore can be varied by angular movement of the plunger about its axis. This movement is effected by the action of a governor or other controlling means on a slidable rack i engaging a pinion i on a sleeve m which is connected to the plunger by a cross pm n.

In the pump above described the barrel is provided with two main ports h which open into an annular feed chamber 0 in the body part, this chamber being supplied with fuel oil by a pipe connected to an inlet 11.

According to the present invention there is provided in the barrel a small supplementary inlet port q. This latter is so disposed as shown relatively to the main ports that it can be closed by the plunger after the latter has moved through a distance of from 0.25-0.5 mm., beyond the position in which it has closed the main ports. Also loaded delivery valve 1' and hence at the injection nozzle in the engine will not commence until after both ports h, q have been closed. But with increasing speed of the pump, the instant of dlscharge will be progressively advanced owing to the resistance of the supplementary port q to flow through it from the pump barrel.

By the expedient above described the automatic advancing of the instant of fuel injection with increasing engine speed can be effected in a very simple and satisfactory manner.

The invention is not, however, restricted to the example described, as the supplementary port may be provided in other ways. Thus, it may consist of a small notch formed in the upper part of the main port or each such port. Further it will be understood that whereas in the foregoing only one pump barrel and plunger, with their associated parts, have been described, each barrel in a multi-plunger pump is provided in like manner with a supplementary port.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A liquid fuel pump having in combination a hollow body part provided with a fuel inlet passage, a barrel arranged in the hollow body part and provided with at least one main fuel inlet port and a restricted supplementary inlet port, both ports being in communication with the fuel inlet passage, and a plunger slidable in the barrel for closing both ports and discharging liquid fuel from the barrel, the restricted supplementary inlet port being disposed in relation to the main inlet port so that it is closed by the plunger shortly after the main port has been closed thereby, and said supplementary inlet port being dimensioned so that when the pump spee is high only a limited amount of fuel can escape therethrough whereas at lower pump speeds a greater amount of fuel can escape through said por 2. A liquid fuel pump as claimed in claim 1, in which the said supplementary inlet port is spaced from the main port.

WILFRID EDWARD WALTER NICOLLS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,361,817 Bolli et al. Oct. 31, 1944 2,382,000 Bremser Aug. 14, 1945 2,384,012 Bremser Sept, 4, 1945 

